Method and apparatus for generating shock waves in a liquid



Dec. 2, 1969 J. KARPOVICH 3,481,784

METHOD AND APPARATUS FOR GENERATING SHOCK WAVES IN A LIQUID Filed June 15, 1966 2 Sheets-Sheet 1 52 FlC-Li INVENTOR.

JOHN KARPOVICH afearmcn 8r mceulloclr Dec. 2. 1969 J. KARPOVICH 3,481,784

METHOD AND APPARATUS FOR GENERATING SHOCK WAVES IN A LIQUID Filed June 15, 1966 2 Sheets-Sheet 2 INVENTOR.

JOHN KARPOVICH BY steamer: fir me a/loch United States Patent 3,481,784 METHOD AND APPARATUS FOR GENERATING SHOCK WAVES IN A LIQUID John Karpovich, 3450 W. Caro Road, Caro, Mich. 48723 Filed June 15, 1966, Ser. No. 557,667 Int. Cl. B08b 7/02 US. Cl. 134-1 28 Claims ABSTRACT OF THE DISCLOSURE Generation of shock waves by explosively boiling a liquid with a low boiling point by bringing it into contact with a high boiling point liquid which i heated to a point above the first liquids boiling point but below its own boiling point.

This invention concerns a method and apparatus for generating shock waves and, more specifically, refers to a method and apparatus for generating high energy shock waves in a liquid by explosively boiling a first body of liquid having a low boiling point in a second body of liquid having a higher boiling point. It has been found that the energy created by this method is most effective and may be used, for instance, to dislodge particles, remove contamination and rust from metal parts, create emulsions, provide dispersions and perform other tasks requiring the presence of high energy shock waves.

Quite specifically, the present invention discloses the generation of shock waves by the use of two liquids which are substantially immiscible, or not soluble in each other, and which have different boiling points. In one embodiment, a first liquid having the higher boiling point is heated to a temperautre above the boiling point of a second liquid which has a lower boiling point. Then, the second liquid having the lower boiling point is added in a small stream or dropwise to the heated liquid having the higher boiling point. The result of the contact between the two liquids is that the liquid with the lower boiling point becomes heated to or above its boiling point (superheated) and explodes into a boil. The initiation of the boiling under these circumstances is an explosive action which manifests itself by the formation of violent shock waves which recur as additional quantities of the lower boiling point liquid are added to the higher boiling point liquid. The shock energy thus generated is the result of the almost instantaneous conversion of the superheated lower boiling point liquid from its liquid phase to the vapor phase.

Typical liquids which have been used include for the liquid having the lower boiling point: water, methanol, cyclohexane, and for the second, higher boiling point liquid: linseed oil, corn oil, cottonseed oil, pigs lard, beef tallow, ethylene glycol phenyl ether, common heat quench oil and the like.

Using the method described hereinabove, it has been possible, for instance, to clean heavily corroded automotive spark plugs and heavily scaled and rusted pipe sections in a relatively short time, whereas such part have heretofore not been cleaned successfully by prior known methods including ultrasonically agitated liquids. Moreover, it has been possible to create stable emulsions, dispersion of particles and carry out other processes which require the generation of powerful and concentrated shock energy.

One of the principal objects of this invention is, therefore, the provision of a new method and apparatus for generating shock energy.

Another important object of this invention is the proice vision of a new method and apparatus for generating shock waves in a liquid.

Another important object of this invention is the provision of a new method and apparatus for providing shock waves by explosively boiling one liquid in another liquid.

Another object of this invention is the provision of a novel method for dislodging particles adhering to an object by subjecting such particles to shock waves generated by an explosively boiling liquid.

A further object of this invention is the provision of a method and apparatus for cleaning articles by immersing such articles in a liquid which is maintained at an elevated temperature and producing explosions within such liquid.

A further object of this invention is the provision of a method and apparatus for generating shock energy using two immiscible liquids having greatly different boiling oints.

Another and further important object of this invention is the provision of a novel method and apparatus for treating an article by immersing such article in a first liquid which is maintained above the boiling point of a second liquid and introducing small amounts of the second liquid into the first liquid whereby the second liquid explosively boils in the first liquid, such boiling generating highly effective shock waves which impinge upon the article and dislodge contamination from the surface of such article.

A still further and other object of this invention is the provision of a method and apparatus for producing emulsions and dispersions by new and novel means.

Further and still other objects of this invention will be more clearly apparent by reference to the following description when taken in conjunction with the accompanying drawings in which:

FIGURE 1 is an elevational view, partly in section, of a typical arrangement for practicing the present invention;

FIGURE 2 is a view similar to FIGURE 1 including certain modifications, and

FIGURE 3 is an elevational view, partly in section, of another arrangement for practicing the invention.

Referring now to the figures and FIGURE 1 in particular, there is shown as vessel 10 which is provided with a lid 12 and which is partially filled with a first liquid 14 having a relatively high boiling point. The liquid 14 is heated by means of a suitable heating means, such as a gas burner 16, which imparts heat to the underside of the vessel 10. A thermometer 18 is provided to monitor the temperature of the liquid 14. A second liquid 20 is contained in a second vessel 22 and this latter liquid can be added to the first liquid via a pipe 24 which is provided with a needle valve 26. A cooling jacket 28 is disposed about the pipe 24 to maintain the second liquid, having a relatively low boiling point with respect to the first liquid 14, cool at the time of it being added to the liquid 14. Numeral 30 identifies a section of a pipe which is immersed in the liquid 14 and which is to be cleaned, and numeral 32 refers to another object immersed in the liquid 14, also for treatment purposes. One of the main features of this invention resides in the fact that both liquids are substantially immiscible, i.e. not soluble in each other.

The liquid 14 having a relatively high boiling point is heated to a temperature above the boiling point of the liquid 20 and when this temperature is reached, the needle valve 26 is adjusted so that the liquid 20 is added to the liquid 14 dropwise or in a small stream. It appears from observations that a drop of the liquid 20, upon reaction into the liquid 14 and being heated by heat transfer therefrom, does not vaporize in one single step. Instead,

upon reaching its boiling point the liquid 20 explosively boils and breaks up into smaller drops which individually explosively boil at a temperature which seems to be above the normal boiling point of the liquid 20 itself, thus providing the energy which is normally associated with a superheated liquid. The explosive boiling produces shock waves which are propagated in the liquid 14. It has been noticed that the liquid 14 can be at a tempera ture which is considerably above the boiling point of the injected liquid 20, yet the injected liquid does not boil until after a substantial time of residence in the hot environment. The violence of the explosive boiling suggests that the injected liquid becomes superheated before boiling is initiated. The temperature attained by the injected liquid drop, before it explodes into the vapor phase, can be lowered by introducing a nucleating agent, such as clay particles, into the liquid 20. This condition will be found desirable when a more gentle treatment of the objects 30 and 32 is desired.

In contrast with the above, very pure and degassed liquids need to be employed in order to elevate the temperature at which the injected liquid explodes into the boil. Under these latter conditions, the injected liquid takes on a maximum of superheat and, therefore, explodes in to the vapor phase with great violence.

The energy produced by the explosive boiling of the liquid 20 in the liquid 14 can be increased considerably by pressurizing the vessel to above atmospheric pressure. To this end, there is provided a pressurizing line 40 connected to the vessel 10 and including a pressure valve 42, a pressurization line 44 including a valve 46 for pressurizing the liquid 20, and a pressure gauge 48 for monitoring the pressurization of the vessel 10. A vapor exhaust line 50 with check valve 52 serves for continuously removing the vapor created by the boiling of the liquid 20. When operating the vessel 10 under pressurized conditrons, the lid 12 is sealed to the vessel using conventional means, such as a soft metallic gasket and suitable compression means well known to those skilled in the art.

It is desirable that the injected lower boiling point liquid have a specific gravity which is higher than that of the heated liquid 14. This condition will cause the injected liquid to drop into and through the higher boiling point liquid, instead of having a tendency to rise to the surface of the liquid 14 and explode thereat with little or no useful etfect upon the objects and 32.

FIGURE 2 shows a slightly modified arrangement wherein the vessel 10 is heated by an electric heating jacket 60. The lower boiling point liquid 20 is injected into the vessel 10 at a point above the level of the liquid 14. A screen 62 is disposed at the entrance of the liquid 20 into the vessel 10 in order to break up the small stream or drops of liquid 20 into finer drops which then by gravity fall through the liquid 14 before the explosive boiling takes place. In this particular arrangement, as stated hereinabove, it is desirable that the liquid 20 have a specific gravity which is greater than that of the liquid 14. Typical liquids which may be used for the liquid 14 comprise: linseed oil, lard, beef tallow, bees wax, cottonseed oil and the like, electrical insulation oil, thermal quench oil, while typical liquids for the liquid 20 include water, methanol cyclohexane, etc. The water and oil combination is particularly useful and readily available.

EXAMPLE 1 In a typical example an eight inch diameter vessel, 9 /2 inch high, contained 2,000 ml. of lard. Water serving for the liquid 20 was injected at a level close to thebottom of the vessel. During a period of thirty minutes, 200 ml. of water was injected. The lard was maintained at an average temperature of about 285 C. The water vapor exhaust 50 was always kept slightly open. The pressure in the vessel was maintained at an average value of about pounds per square inch by means of the vapor created and additional air pressure. The explosive boiling which occurred can be described as very sharp and snapping. Heavily corroded and contamianted automotive spark plugs inserted in the vessel at the beginning of the test were found to be clean and free of foreign particles at the end of the period stated. Thus, a most effective cleaning action occurred.

' EXAMPLE 2 A cleaning vessel of 2 in. diameter contained 240 ml. of cottonseed oil. Water was injected from the side, substantially as shown in FIGURE 1. During a period of thirty minutes 75 ml. of water was added. The cottonseed oil was maintained at an average temperature of 295 C. and at a pressure of about 32 pounds per square inch. Both steam and air was used to maintain the pressure. The cleaning results were excellent.

EXAMPLE 3 EXAMPLE 4 A cleaning vessel 15 inch diameter by 7 inch high contained cottonseed oil of 2 inch depth. Water was injected by means of a single injector from the side of the vessel, a total of 400 ml. being used. The average temperature of the oil was 290 C. and the vessel was pressurized to about 15 pounds per square inch gauge. The parts to be cleaned were spread out over the entire area of the vessel and, once again, good cleaning results were noticed.

The above enumerated experiments and other tests carried out revealed clearly that heavy deposits and soil can be removed from the inside of pipes and that rust and corrosion can be removed from parts which normally show no appreciable change upon exposure to ultrasonic cleaning techniques. Hence, the same arrangement may be used, for instance, to clean the inside walls of the vessel 10 itself. This method, therefore, lends itself to the cleaning of large processing tanks. It appears that the explosive boiling of liquids creates high energy shock waves which contain more peak energy than that which is available with the heretofore known cleaning processes.

The rate at which the low boiling point liquid 20 should be injected from the vessel 22 into the vessel 10 can be judged by ear. The flow is controlled by means of the valve 26 so that the explosions are adjudged to be most violent. A more automated method employs a sound level or vibration pickup device coupled to a servo mechanism for controlling the valve 26 so that the injected liquid 20 flows at a rate which produces maximum explosive noise.

As water is added to the heated oil an emulsion is created and, therefore, the present apparatus and process may be used also for producing stable emulsions, for making dispersions in liquid and for causing chemical reactions. Along this line, dispersions of clay in oil have been made and paint pigments have been dispersed in paint vehicles.

Since the liquids used are immiscible, a further modification comprises the placing of the liquid 20 in contact with the liquid 14 at a temperature when the latter liquid is below the boiling point of the liquid 20. Both liquids then are heated while in contact with one another and the portions of the liquid 20 will come to a boil as the boiling point of the latter liquid is reached and exceeded. Cleaning action results.

It will be apparent that for obtaining most satisfactory results, the liquids should have widely different boiling points and that the boiling point of the liquid should be relatively low. Also, the conversion of the liquid 20 from its liquid phase to its vapor phase should be rather instantaneous and accompanied by the release of a large amount of energy which is propagated in the liquid 14.

'One of the interesting phenomena noted concerns the discovery that oil which is not a cleaning liquid causes the objects immersed therein to become clean. Thus, another suitable liquid may be substituted which not only acts as a medium for propagatingthe shock energy but which, by virtue of its chemical characteristics, also serves as a cleaning agent or solvent for the contamination adhering to the article to be cleaned.

Although a single injection line 24 is depicted in the illustration, a plurality of such lines may be used without deviating from the principle described. In small vessels of the type described above, a single injector has been found adequate. In very large vessels, however, multiple injectors are preferred to provide good dispersion of the low boiling point liquid.

FIGURE 3 illustrates a further embodiment of the present invention, which arrangement has been used for injecting encapsulated drops of a low boiling point liquid into the high boiling point liquid. Referring now to this figure, a lower vessel portion 70 is partially filled with a high boiling point liquid 72, such aslinseed oil, which is heated by an electric immersion heater '74. A thermometer 76 monitors the temperature of the liquid 72. Parts 78 to be treated or cleaned are disposed in contact with the liquid 72. The upper end of the vessel portion 70 is provided with a neck section 80 which is fitted with a side arm 82. A plurality of small frangible capsules 84 are disposed in the side arm '82, each such capsule containing a small amount of a low boiling point liquid, for instance water. The capsules are injected into the vessel and into the liquid 72 by means of a plunger 86 which, for such purpose, is advanced toward the center axis of the vessel. A capsule 88 is shown as just released and falling through the liquid 72.

The vessel is provided, further, with a muffler '90 which includes two splash bafiles 92 and 94. The purpose of the mufiler is to slow down the splashed liquid 72 caused by the explosions which occur upon thelow boiling point liquid being injected. The mufiler leads to a vapor exhaust duct 96 which is provided with a condensate trap 98 and a valve 99 for removing the condensate.

As indicated hereinabove, the apparatus is particularly suited when the low boiling point liquid, such as water, is encapsulated in a frangible container, e.g., glass, and this encapsulated liquid is introduced into the heated high boiling point liquid. The encapsulated liquid, upon contact with the heated liquid 72, becomes heated until the generated vapor pressure causes the capsule to explode. This initial explosion itself generates a violent shock wave. However, as the capsule explodes some of its contents enter the vapor phase, much of its contents are ejected throughout the hot liquid environment in the form of small liquid droplets which subsequently explode into a boil. This sequence causes a very eifective cleaning action. In this case also, the two liquids should be substantially immiscible, and the lower boiling point liquid should preferably be of a slightly higher density. The initial explosion of the glass capsule is a very effective way to disperse the small liquid droplets throughout the high boiling point liquid environment.

An important feature of this system is that very clean and degassed liquid can be encapsulated, thus minimizing nucleation sites. Another feature of the encapsulation resides in the fact that cleaning ingredients, such as soap, acid, base, and other aids may be provided in measured quantities. It has been observed that when two or more capsules are introduced at the same time, the first explosion does not usually initiate the explosion of other capsules. This leads to the arrangement wherein a quantity of capsules with different container thicknesses, or filled with different amounts of liquid, are provided, thus causing time-spaced explosions.

The injection of water filled glass capsules in the vessel portion 70 provides a first explosion which rather extensively splashes the high boiling point liquid. The muffier 90 prevents the loss of the high boiling point liquid. The capsule injector plunger 86 is provided with locking means (not shown) so as not to be driven out by the expanding vapor pressure. After a capsule is injected and it explodes, explosion from secondary droplets can be heard for a period from 2 to 5 minutes. In the preferred arrangement, the next capsule, or set of capsules, is not introduced until the explosive boiling essentially comes to a stop.

In a typical operation eight capsules, 1 ml. each, were introduced over a period of 30 minutes causing the removal of soil 0.008 inch thick from a 4 inch diameter rusty rod. In another example, six capsules, 2 ml. each, were introduced during a period of 28 minutes with similar results. In a third example, six capsules, 5 ml. each, were introduced during a period of 26 minutes with substantially the same results. In these examples, the capsules were filled with water, the liquid 72 was linseed oil and the dimensions of the vessel were as follows: lower vessel portion 70eight inches diameter by nine inches high; neck -three inches diameter by nine inches high; mufiler eight inches diameter by six inches high.

It should be understood that the above dimensions and operating conditions are stated for illustrative purposes only and that no limitation as to size shall be implied. The heretofore described invention will be found to operate under widely varying conditions as long as the principle described is adhered to.

While there have been described and illustrated certain preferred embodiments of the present invention and certain modifications have been indicated, it will be apparent to those skilled in the art that still further changes and modifications may be made therein without deviating from the broad principle and intent of this invention, which shall be limited only by the scope of the appended claims.

What is claimed is:

1. The method of generating shock waves comprising the steps of:

(a) bringing two immiscible liquids having substan tially different boiling points in contact with one another, and

(b) causing the liquid having the lower boiling point to boil in the liquid having the higher boiling point, whereby such boiling produces shock waves which are propagated in the higher boiling point liquid.

2. The method of generating shock waves in a liquid comprising the steps of:

(a) providing a first body of liquid having a first boiling point, and a second body of liquid immiscible in said first body of liquid and having a second boiling point which is substantially below the boiling point. of said first body of liquid, and

(b) causing said second body of liquid while in contact with said first body of liquid to explosively boil whereby to generate shock waves which are propagated in said first body of liquid.

3. The method of generating shock waves in a liquid as set forth in claim 2 wherein said first and second bodies of liquid are brought in contact with one another at a temperature below the boiling point of said second body of liquid, and both bodies of liquid are heated subsequently to cause the second body of liquid to boil explosively in the first body of liquid.

4. The method of generating shock waves in a liquid as set forth in claim 2 wherein said second body of liquid is added to said first body of liquid in relatively small quantities.

5. The method of generating shock waves in a liquid as set forth in claim 2 wherein said second body of liquid is caused to boil by heat transfer from said first body of liquid.

6. The method of generating shock waves in a liquid as set forth in claim 2 wherein said bodies of liquid when in contact with one another are maintained substantially at atmospheric pressure.

7. The method of generating shock waves in a liquid as set forth in claim 2 wherein said bodies of liquid when in contact with one another are maintained at above-atmospheric pressure.

8. The method of generating shock waves in a liquid as set forth in claim 2 wherein said second liquid has a specific gravity which is greater than that of said first liquid.

9. The method of generating shock waves in a liquid as set forth in claim 2 wherein said second liquid has a specific gravity which is greater than that of said first liquid and is added to said first liquid in such a manner as to cause it to fall through said first body of liquid prior to its boiling.

10. The method of generating shock waves in a liquid as set forth in claim 2 wherein said second body of liquid includes a nucleating substance.

11. The method of generating shock waves in a liquid as set forth in claim 2 wherein said second body of liquid is degassed before contact with said first body of liquid.

12. The method of generating shock waves in a liquid as set forth in claim 2 wherein said second liquid is an aqueous liquid.

13. The method of generating shock waves in a liquid as set forth in claim 2 wherein said first liquid is oil.

14. The method of generating shock waves in a liquid as set forth in claim 2 wherein said first liquid is fat.

15. The method of generating shock waves in a liquid as set forth in claim 2 wherein said first liquid is wax.

16. The method of generating shock waves in a liquid as set forth in claim 2 wherein said first liquid is oil and said second liquid is water.

17. The method of generating shock waves in a liquid as set forth in claim 2 wherein said first liquid is an organic liquid and said second liquid is water.

18. The method of generating shock waves in a liquid as set forth in claim 2 wherein said second body of liquid is caused to boil by placing it in contact with said first body of liquid when said first body is at a temperature substantially above the boiling point of said second body and said second liquid is substantially below its boiling point.

19. The method of generating shock waves in a liquid as set forth in claim 18 wherein said second body of liquid is added in timed relation to said first body of liquid in the form of drops.

20. The method of generating shock waves in a liquid as set forth in claim 18 wherein said second body of liquid is added to said first body of liquid in a relatively small stream.

21. The method of generating shock waves in a liquid comprising the steps of:

(a? providing a first body of liquid having a first boiling point;

(b) providing a second body of liquid encapsulated in a container, said second liquid being substantially immiscible in said first liquid and having a boiling point which is substantially below the boiling point of said first liquid;

(c) raising the temperature of said second body of liquid to above its boiling point while disposed in encapsulated-form in said first body of liquid, whereby to cause said container to fracture, the resulting dispersion of said second liquid and explosive boiling thereof in said first liquid producing shock waves which are propagated in said first body of liquid.

22. The method of generating shock waves as set forth in claim 21 wherein said container is frangible and is made of glass.

23. The method of generating shock waves as set forth in claim 21 wherein said second liquid is water.

24. The method of generating shock waves as set forth in claim 21 wherein said container when first brought in contact with said first body of liquid is at a lower temperature than said first body of liquid, and the volume of liquid contained in said container is small in relation to the volume of said first body of liquid.

25. The method of generating shock waves as set forth in claim 21 wherein said second body of liquid is provided by a puralityof frangible containers which are placed into said first body of liquid, each such container containing a relatively small amount of the second liquid.

26. The method of generating shock waves as set forth in claim 25 wherein said containers are brought in contact with said first body of liquid substantially at the same time and the containers are constructed to fracture in timed relation to cause the sequential dispersion of small amounts of the second liquid.

27. The method of generating shock waves in a liquid as set forth in claim 26 wherein said timed relation is provided by said frangible containers having different wall thicknesses.

28. The method of generating shock waves in a liquid as set forth in claim 26 wherein said timed relation is provided by varying the amount of liquid disposed in said frangible containers.

References Cited UNITED STATES PATENTS 2,664,274 12/1953' Worn et a1. 1654-84 3,156,248 11/1964 Rand 134-1 3,227,649 1/1966 Ghormley l65l MORRIS O. WOLK, Primary Examiner I D. OLSEN, Assistant Examiner US. Cl. X.R. 

